The state and future of Mars polar science and exploration

As the planet's principal cold traps, the martian polar regions have accumu lated extensive mantles of ice and dust that cover individual areas of simi lar to 10(6) km(2) and total as much as 3-4 km thick. From the scarcity of superposed craters on their surface, these layered deposits are thought to be comparatively young-preserving a record of the seasonal and climatic cyc ling of atmospheric CO2, H2O, and dust over the past similar to 10(5)-10(8) years. For this reason, the martian polar deposits may serve as a Rosetta Stone for understanding the geologic and climatic history of the planet-doc umenting variations in insolation (due to quasiperiodic oscillations in the planet's obliquity and orbital elements), volatile mass balance, atmospher ic composition, dust storm activity, volcanic eruptions, large impacts, cat astrophic floods, solar luminosity, supernovae, and perhaps even a record o f microbial life. Beyond their scientific value, the polar regions may soon prove important for another reason-providing a valuable and accessible res ervoir of water to support the long-term human exploration of Mars. In this paper we assess the current state of Mars polar research, identify the key questions that motivate the exploration of the polar regions, discuss the extent to which current missions will address these questions, and speculat e about what additional capabilities and investigations may be required to address the issues that remain outstanding. (C) 2000 Academic Press.